page_title: QF 2-pounder naval gun
section_title: QF 2-pounder Mark VIII
hierarchical_section_title: QF 2-pounder naval gun / QF 2-pounder Mark VIII
caption_attribution_description: English: QF 2 pounder Mk. VIII single mount from Flower-class corvette HMCS Kamloops, displayed in Canadian War Museum.
context_page_description: The 2-pounder gun, officially designated the QF 2-pounder and universally known as the pom-pom, was a 40-millimetre British autocannon, used as an anti-aircraft gun by the Royal Navy. The name came from the sound that the original models make when firing. This QF 2-pounder was not the same gun as the Ordnance QF 2 pounder, used by the British Army as an anti-tank gun and a tank gun, although they both fired 2-pound, 40-millimetre projectiles.
context_section_description: The Royal Navy had identified the need for a rapid-firing, multi-barrelled close-range anti-aircraft weapon at an early stage. Design work for such a weapon began in 1923 based on the earlier Mark II, undoubtedly to utilise the enormous stocks of 2-pounder ammunition left over from the First World War. Lack of funding led to a convoluted and drawn-out design and trials history, and it was not until 1930 that these weapons began to enter service. Known as the QF 2-pounder Mark VIII, it is usually referred to as the "multiple pom-pom". 
  The initial mounting was the 11.8 to 17.35 ton, eight-barrelled mounting Mark V (later Mark VI), suitable for ships of cruiser and aircraft carrier size upward. From 1935, the quadruple mounting Mark VII, essentially half a Mark V or VI, entered service for ships of destroyer and cruiser size. These multiple gun mounts required four different guns and were nicknamed the "Chicago Piano". The mount had two rows each of two or four guns. Guns were produced in both right- and left-hand and "inner" and "outer" so that the feed and ejector mechanisms matched. 
  Single-barrelled mounts, the Mark VIII (manual) and Mark XVI (power operated), were also widely used, mainly in small escorts (such as the Flower-class corvettes) and coastal craft (especially early Fairmile D motor torpedo boats). The Mark XVI mounting was related to the twin mounting Mark V for the Oerlikon 20 mm cannon and the "Boffin" mounting for the Bofors 40 mm gun. Magazines ranged from 140 rounds per gun for the eight-barrelled mount to 56 rounds for the single mounts. This large ammunition capacity gave the eight-barrelled mount the ability to fire continuously for 73 seconds without reloading. A high velocity (HV), 1.8 lb (820 g), round was developed for the pom-pom, just prior to World War II, which raised the new gun muzzle velocity from 2,040 ft/s (622 m/s) to 2400 ft/s (732 m/s). 
  Many older mountings were modified with conversion kits to fire HV ammunition, while most newly manufactured mounts were factory built to fire HV ammunition. A mount modified or designed for HV ammunition was given a '*' designation; for example a Mk V mount modified for HV ammunition would be designated Mk V*.
caption: QF2 Mk. VIII single mount from HMCS Kamloops, displayed in Canadian War Museum
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